Dylan Frittelli, struggling through a difficult PGA Tour season, withdrew from the Memorial tournament on Thursday after going 15-over par in 14 holes at Muirfield Village.The 32-year-old South African has missed the cut 11 times and withdrawn three times in his past 18 starts with his best finish in the span a share of 14th at the Phoenix Open in February.Frittelli withdrew due to illness, according to a PGA Tour statement.After opening with three pars at the Dublin, Ohio, layout, Frittelli made bogeys at the par-3 fourth, where he missed the green, and par-5 fifth, where he found water with his third shot.Frittelli sank a birdie putt from just inside seven feet at the sixth but followed with a three-putt bogey at the par-5 seventh and found water at the ninth on his way to a double bogey.He opened the back nine with back-to-back triple bogeys, finding water twice at the par-5 11th, and made double bogey after another splashdown at the par-3 12th.He made bogey at 13 and a double bogey at 14 before stopping after an errant tee shot way left at the par-5 15th - his 72nd stroke over the par-72 layout.Frittelli withdrew at the Heritage in April after an opening 80, his worst round of the season, and pulled out after two rounds at Pebble Beach in February.Frittelli won the PGA John Deere Classic in 2019 and had fifth-place finishes at the 2020 Masters and 2021 Open Championship. Leading scores after Thursday's first round of the PGA Tour Memorial tournament at Muirfield Village in Dublin, Ohio (USA unless noted, par-72): 67 - Davis Riley68 - Matt Wallace (ENG)69 - Danny Willett (ENG), Adam Hadwin (CAN), Mark Hubbard, Shane Lowry (IRL), Austin Eckroat, David Lipsky, Jordan Spieth70 - Patrick Rodgers, Justin Suh, Wyndham